Clinical and laboratory findings in eight patients with childhood common variable immunodeficiency and autoimmune disease are described. Six of the eight patients had initial signs of the disease, persistent secretory diarrhea, recurrent upper respiratory tract infections, or both, in the first year of life. Autoimmune manifestations included idiopathic thrombocytopenia (4/8), hemolytic anemia (3/8), secretory diarrhea (4/8), arthritis (2/8), chronic active hepatitis (2/8), parotitis (2/8), and Guillain-Barré syndrome (2/8). In addition to the expected sinusitis, otitis, and pneumonia caused by encapsulated bacteria, these patients also had severe infections with viruses of the herpes group. Most of these patients had lymphadenopathy, splenomegaly, growth failure, and failure to develop secondary sexual characteristics. Laboratory studies demonstrated a significant increase in the ratio of T cells expressing the T helper phenotype (OKT4) to T cells expressing the T suppressor-cytotoxic phenotype (OKT8) (T4/T8). This increase could be attributed to a decrease in the absolute number of T8 cells. Additional findings included fluctuating levels of serum immunoglobulins and markedly diminished in vitro antibody production by B cells. The clinical course was relapsing and remitting, and dominated by the autoimmune manifestations of the disease. This group of patients constitutes a distinct subset of children with hypogammaglobulinemia, a subset with a complex, multisystemic disorder associated with significant morbidity and mortality.